Control mechanism



Oct. 10, 1939. E. M. MILLER 2,175,720

CONTROL MECHANISM Filed May 4, 1936 5 Sheets-Sheet 1 4O T42 5S 32 Oct.10, 1939. E. M. MILLER 2,175,720

CONTROL MECHANISM Filed May 4, 1936 5 Sheets-Sheet 2 h w In? Ill 72 72 Aswam tor,

Ernest M ML'ZZGT' Gum;

Oct. 10, 1939. E. M. MXLLER 2,175,720

CONTROL MECHANI SM Filed May 4, 1936 5 Sheets-Sheet 3 We IG7 Ernest MMiller GUM/win Oct. 10, 1939. E. M. MILLER CONTROL MECHANISM Filed May4, 1956 5 Sheets-Sheet 4 ch to:

Oct. 10, 1939.

E. M. MILLER CONTROL MECHANISM Filed May 4, 1938 5 Sheets-Sheet 5 [ISOflsl 192 I IISG VVVI I awe/Mon E'f'fPSZ'MMiiZQf Patented Oct. 10, 1939UNITED STATES "PATENT OFFICE CONTROL MECHANISM Application May 4, 1936,Serial No. 77,758

21 Claims.

10 adapted to be used with other heat producing devices in the generalart of heat control.

One object of this invention is the provision of an improved connectionbetween a condition responsive element or member actuated thereby andcircuit controlling mechanism whereby, upon motion of the conditionresponsive element within predetermined limits, the circuit controllingmechanism will be actuated, but upon motion in excess of such limits,the element may continue to move without imparting further movement tothe circuit controlling mechanism.

A further object resides in the provision of a mechanism adapted tofunction as set forth in the preceding paragraph in conjunction with alongitudinally movable bar or rod actuated by a thermostatic element.

A further object is the provision of improved means actuated by athermostatic element through a linearly movable member and the con- 1nection as above set forth to actuate a plurality of contacts, one ormore of which moves to open position and the others of which move toclosed position on condition'change in one direction, the motion beingreversed upon condition change l in the opposite direction, so arrangedthat the closing of certain of the contacts occurs before opening ofothers upon condition change in one direction and the'others closesubsequent to the opening of the first mentioned contacts upon motion inthe opposite direction.

A further object is the provision of an improved safety switchcomprising a novel arrangement of elements in association with thecontacts above mentioned to preclude actuation of a fuel burningmechanism, such as an oil burner,

through closure of these contacts, after a predetermined time, uponcombustion failure.

A more specific object is the provision of such a safety switch soarranged that upon resetting by a manual reset lever all. stress isexerted directly on the lever and motion transmitted to the movableparts directly therefrom rather than through other associated elementsor connections.

An additional object is the provision of a therr mo'static elementadapted to provide linear motion to an element in association with themechanism accomplishing the objects as set forth above which may beencompassed in a relatively small space and inserted into said spacethrough a relatively small aperture.

A further object is the mounting of the structures above referred to,and to be described hereinafter, in a single relatively compact housingin such a manner that the overall dimensions of such a housing arematerially reduced as compared to those of analogous structures in theprior art and in such a fashion that all the parts are readilyaccessible for adjustment or replacement.

Other objects will in part be obvious and in part pointed outhereinafter.

The invention, accordingly, consists in the features of construction,combinations of elements and arrangements of parts as will behereinafter described and shown in the accompanying drawings and thescope of the application of which will be indicated by the appendedclaims.

In the accompanying drawings wherein is shown, illustratively, oife ofthe various possible embodiments of this invention:

Figure 1 is a side elevationoi a stack or flue adjacent a furnace orother source of heat having mounted thereon a structure embodying theinstant invention, certain parts thereof being shown in section;

Figure 2 is an enlarged front elevational view taken along line 22 ofFigure 1 as viewed from theright;

Figure 3-is'an enlarged side elevation taken along line 33 of Figure 2from the right, cer- 85 tain parts thereof being omitted;

Figure 4 is a sectional view taken along line 4-4 of Figure 3 viewedfrom the left, certain parts being omitted;

Figure 5 is a side sectional view taken along line 5-5 of Figure 2 asviewed from the right;

Figure 6 is a side elevational view of the mechanism shown in Figure 2as seen from the right along line 6-6, certain parts being omitted;

Figure '7' is a sectional view along line 1-1 of 46 Figure 2; I Figure 8is a front view of certain of the parts shown in Figures 6 and 7,certain portions thereof being moved out of operative position to showother parts more clearly and other parts thereof being removed. Figure 9is an exploded perspective view of certain parts shown in elevation inFigure 6 and omitted in Figure'8;

Figure 10 is a side elevational view of the structure shown in Figure 2as seen from the left along line ill-Alt), certain parts being omitted;

Figure 11 is a view taken along line li-ll of Figure 10 as viewed fromthe bottom;

Figure 12 is a perspective view of certain portions of the structureshown in Figure 11 in a different position of adjustment;

Figure 13 is a schematic side elevation of one of the elements shown inFigure 11 as taken along line l3l3 of Figure 11;

Figure 14 shows a modified form of certain features of the invention,and

Figure 15 is a schematic view showing diagrammatically the wiringconnections of the structure of the instant invention in associationwith one form of control system to which it may be applied.

Similar reference characters refer to similar parts throughout theseveral views of the drawings,

Referring now particularly to Figure 1, there is generally indicated at23 a fragment of a stack or flue or other device associated with afurnace or other source of heat having an aperture 2i passedtherethrough and a mounting bracket comprised of a flange 22, an annulus23 and a set screw 24 rigidly secured thereto in any desired manner.Passed through annulus 23 is a sleeve 25 having projections 25 thereonto limit the depth of insertion of sleeve 25 into stack 20. Rigidlysecured to one end of sleeve 25 is a mounting plate 21 to which issecured, as by screws 28, a supporting flange 23 to which in turn isdetachably secured a casing 33 containing certain mechanism to behereinafter described. The opposite end of sleeve 25 has rigidlyassociated therewith a mounting bracket 3! which comprises a laterallyextending portion 3m and downwardly depending portion 32. An aperture 33is located substantially at the junction of portions 3la and 32. Abimetal element, generally indicated at 34, comprises a hooked portion35 which is adapted to be inserted in aperture 33, a downwardlydepending portion 36, a convoluted portion 31, a reentrant linearportion 38 and an upwardly extending portion 39 bent into a hook 40. Anaperture 4| in hook 40 accommodates the reduced end 42 of a rod 43 whichextends inwardly through sleeve 25. A pin 44 passed through a suitableaperture in end 42 holds the parts in related assembly.

From this it will be seen that as the temperature in stack 20 changes,bimetal element 34 expands or contracts, and due to the configurationabo ve described, such expansion or contraction is transmitted to rod 43in the form of linear movement back and forward in sleeve 25. Convolutedportion 3'! provides a substantially large area of bimetal to transmit acorrespondingly large amount of motion to rod 43, but due to theconfiguration above described, the element may be readily passed throughaperture 2| or, in other words, into a space through any aperturethrough which sleeve 25 may pass. In the illustrative embodiment, thearrangement of the bimetal is such that upon temperature rise in stack20, bimetal element 34 expands to force rod 43 outwardly with respect tostack 20 through sleeve 25 in the direction indicated by the arrow H,and, conversely, as the temperature decreases, element 34 contracts todraw rod 43 further into the stack 20. It will readily be understood,however, that by reversing the position of the component metals ofelement 34 art mac with respect to the curvature thereof, an oppo siteeffect may be achieved, if desired.

In Figure 14, there is shown a modification of 'the structure abovedescribed adapted to be mounted on a plane surface, such as a furnacedoor 63. In this form, the thermostatic element comprises a disk 5tthrough which is passed the reduced end of a rod 5i. Disk MD is suitablymounted in a flange 52 and has superposed about its periphery a ring 18and a heat resisting gasket the parts beingheld in related assembly asby means of screws 53. This structure is substantially of the typedisclosed in Patent No; 1,765,056 to Lewis L. Cunningham entitledAutomatic device in which patent this operation is fully set forth.Flange 52 is secured to a casing 55 which is in its essentials analogousto sleeve 25, above described. A spring Referring now to Figure 2, aninsulating panel 63 is contained within supporting flange 29 and securedthereto in any suitable manner. Panel til carries a conventionaltransformer, generally indicated at iii, a relay mechanism, generallyindicated at 52, a safety switch, generally indicated at 63, and contactmaking and breaking means, generally indicated at 6 1, the latter threeof which mechanisms will be more fully described hereinafter. Aplurality of terminals to permit connection of the device to associatedmechanism to be hereinafter described are also provided in panel 63.

Referring now to Figure 3, the end of rod 43 opposite bimetal element 34is screw threaded into an insulating block 65, into the other end ofwhich is also screw threaded an end of a second rod 66. A spring 61positioned between two cup washers 68, one of which abuts block 65 andthe other of which abuts panel 60, serves to hold rod 4-3 rigidlyagainst hook 411 of bimetal element 34 in order that slight temperaturevariations may be transmitted directly and substantially immediately tored 66. Referring back to Figure 1 1, rod 5| operated by disk 50 islikewise screw threaded into an insulating block 65 which in turnoperates a rod 66, as in Figure 3. However, spring 67 of Figure 3 is notrequired in the structure shown in Figure 14 since spring 56 serves ananalogous purpose. The end of rod 66 opposite block 65 extends through asuitable aperture 69 in panel 60 and passes between a roller 10, asbetter shown in Figure 4, and two arcuate surfaced depending portions 72carried by a second roller 13. Axles 74 and 15 pass through rollers 10'and 13, respectively, and are journaled, as better shown in Figure 5, ina suitable U shaped bracket 16 secured to panel 60 in any suitablemanner, as by screws 11 (see Figure 3). Springs 18 and 19 engageadjacent ends of axles l4 and 15 and serve to draw rollers 73 and, 10towards each other and, consequently, insure a relatively tightfrictional engagement of portions 12 and roller 70 with rod 66.

Mounted on roller 10 for rotation therewith is an extending arm 99 whichhas secured thereto, as by a rivet 99, a leaf spring contact 91 adaptedtoabut a stationary contact 99 which is provided with a shoulder 99 tolimit motion of lever 99 in a direction towards panel 99 and securedthereto as by a binding post 99 and nut 99. A stop member 9i suitablysecured to panel 99 serves to limit motion of arm 99 in a direction awayfrom contact 99.

Depending portions 12 comprise the lower extreniities of a second arm 92which has secured thereto, as by a rivet 93, a pair of leaf springcontacts 99\and 99, one on either side adapted to engage respectivelycontact screws 99 and 91 carried in turn by supporting members 99 and 99which are secured as by screws and nuts I99 and I9I- to panel 99. Anaperture 99 is provided in arm 92 to permit passage of contact screw 91therethrough to engage contact 99. An adjustable screw l92 is passedthrough a suitable threaded aperture in the upper extremity of arm 92and serves to limit the motion of arm 92 in a direction towards panel99, outward movement thereof being limited by member 99.

An extending portion I93 of arm 92 carries a mercury switch clip I99,secured thereto as by a rivet I99. Clip I99, in turn, carries a mercuryswitch I99 (see Figure 5) and the arrangement is such that switch I99 istilted to open and closed positions by the movement, as will behereinafter described, of arm 92. A screw I91 adapted to engage asuitable threaded aperture in clip I99 passes through a slot I99 in armI99 and by ad- :lustment of screw I91 with respect to slot I99 the angleof inclination of switch I 99 may be adjusted.

From the foregoing it will now be seen that motion of thermostaticelement 99 is transmitted through rod 93 and block 99 to rod 99 and thatas rod 99 is moved towards the left, as viewed in Figure 3, in thedirection indicated by the arrow H occasioned by temperature rise, asabove stated, contacts 99 and 99 will move to the right and breakcontact with their respective contacts 99 and 91. Simultaneously, arm 99will move to the right and contact 91 will engage contact 99. Upon suchmotion, mercury switch I99 will be tilted through extension I99 of arm92 to open position. The above movements are occasioned by thefrictional engagement of rod 99 with depending portions 12 and roller19, respectively, as above stated, these elements being held infrictional engagement with rod 99 by springs 19 and 19. Continuedmovement of rod 99 to the left will cause the abutment of stop screw I92with panel 99 and, likewise, the engagement of arm 99 with shoulder 99of contact 99, which abutments will preclude further motion of arms 92and 99. Continued motion of rod 99 to the left occasioned by a furtherrise in temperature will merely cause rod 99 to slip between rollers 19and depending portions 12 without injury to the mechanism since springs19 and 19 are of insuilicient strength to hold the members in such rigidassembly as to occasion any strain on the component parts.

diately moves arm 92 and its associated contacts 99 and 99 to' the leftinto engagement with their respective opposed contacts 99 and 91 andalso causes a corresponding immediate-, movement of arm 99 to breakcontacts 91 and. 99. Stop 9I limits motion of arm 99 and correspondinglythe inturned portion of member 99- which accommodates contact 91precludes undue outward movement of arm 92. Further motion of rod 99 tothe right simply causes slippage of the parts as described above.

It may here be pointed out that rod 99 is preferably of a lengthsuflicient to preclude all possibility of its passing entirely frombetween portions 12 and roller 19, since the motion to the right uponcooling is limited by the abutment of hook 99 with portion 39 ofthermostatic element 39.

The arrangement of the above apparatus is such that the various contactsclose and/or open in predetermined timed relationship, and in thepreferred embodiment of the invention upon movement of rod 99 to theleft, contact 99 first moves away from its opposed contact 99, contact91 then engages contact 99, contact 99 moves away from contact 91 andmercury switch I99 then assumes its open circuit position. Upon movementof rod 99 to the right, contact 91 first breaks from contact 89, mercuryswitch I99 moves to closed circuit position, contacts 99 and 99 make andcontacts 99 and 91 then make.

It will thus be seen that there is an overlapping contact upon movementof rod 99 to the left in order to maintain a circuit or circuits closedat all times, but that there is non-overlapping contact upon movement ofrod 99 to the right and that consequently immediately upon such movementwhich, as above stated, is occasioned by a fall'in temperature adjacentthermostatic element 39, a circuit or circuits through the variouscontacts above mentioned will be immediately broken. The reason for thesequence 'of operation above set forth and the advantages achievedthereby will be pointed out hereinafter. It will be readily understoodthat numerous factors of the positioning and arrangement of elementsenter into the determination of the proper relationship of the partswith respect to each other in order to produce the above describedsequence. Such factors may include the predetermination of the diameterof rollers 19 and the radius of curvature of depending portion 12 sinceit will be understood that where, as here, one of the rollers is of lessdiameter than the other, a'more rapid travel will be imparted to itsassociated contact arm. The length and positioning of contact screws 99and 91 may also have a bearing upon the sequence of operation, aslikewise, may the angle of inclination of mercury switch I99 withrespect to extending portion I93 of arm 92.

The above sequence may be changed to suit the requirements of any systemwith which the mechanism is associated by the mechanical arragement andpositioning of the parts and elements above mentioned. Likewise, theduration of the intervals between the opening and/or closing of thevarious contacts may be varied in the same manner.

Referring now to Figures 6 to 9, inclusive, wherein are shown variousportions of relay 92, a laminated core II9 is secured topanel 99, as bythe engagement of nuts III with suitable threaded extensions II2 on thelegs of core II9. A coil 9 is wound about one of the legs of core' I I9and a suitable spacer ring H9 is positioned adjacent coil III. Anarmature H9 is pivotally mounted-as by a pivot pin 9 which passesthrough suitable apertures in a bracket in secured to armature H9 and abracket I99 secured to core .9. A pair of contact carryin members I" aresecured, as by nuts H9, to

panei 99 and carry at their outer ends contacts it An contact suitablynsulated t'loued be i as by able threaded e'o stile "11g block ,1. m Krivet lod, e a t t e3 1,

1 w r snotvn "neped e r tact ctremities insulating 1 related co act 112?ma to be do aperture HS 325 eccommod' te movem o to limit 'y f om coreAs in- HQ by abutment suieting blocl: be accommodated. assembly. Screwsand suitable indentetio member and contact carrying member 9respectively, and thence pass t rough irisuletlng block 0 intoengagement with above mere tioned apertures in bracket llEla pivoted onrelay core l lil.

As better shown in Figure If, H3 passed through bloel: l and terminatesin a hook shaped portion m adjacent, and eligriment with, in @ne end ofs, spring engages hoot; G ll and the other end engages a suitableaperture M3 in depending lug M5 secured to core Md. The pi pose of snrig M2 is to preelude xcessive movement 05 meture J35 with respect to HS,in other Words, to preclude relay vibration. arrangement is such thatspring l lil pulls inwardly in line directly in alignment with A H5whereby it exerts n undue stres either open or close erm As will e lolsi. port contact mem ers engagement v] ly extending portion Alsocarried. by pin l which has 21/ lateral on a vertically extendingportion d to 2). Extension 586 is edapte b er certain circumstances, byan projection l3? of member lSl. Bracket member 3 3 3 a color portion MSalso comprised of insulating ieli. A mounting member 115% is connectedto bracket 15d, es by a screw HE and a screw 7 S9 in slot Ml whichletter permits adjustment of the assembly with respect to extensionJ5EE. Two bimetallic strips W6 and H2, secured together as by a studi713, are suitably secured to mounting" member 9-39. Mounted adjacentmemoer H2 is a resistance element comprised of a coil ll l havingwiresH6 leading thereto from suitable terminals 376 curried by it dependingiretsul ting panel l'll, secured in any desired manner to bracket lull.Rigidly secured to the free end of strip W2 end on the opposite side ofcoil i7 3 a third bimetal element HS, which has as better shown inFigure 13, an upwardly extending; portion H9 adopted, under carteeircumst rices be set forth hereinafter, to I I14, as will be laterdescribed, the bimetal assembly comprised of elements I1I, I12 and I18tends to expand and the arrangement, as above stated, is such that suchexpansion causes the assembly to move in a direction away from contactcarrying members I54 and I55. Upon such motion, portion I19 will movebeyond the end of extension I65, which due to the spring pressureexerted on portion I68 by spring contact carrying member I54, willimmediately drop into the position shown in Figure 12, which permitscontacts I58 and I59 to separate and due to the pressures of arcuateportion I62 against extending portion I63 of spring contact arm I55,contact I59 will be precluded from moving with contact I58 as the lattermoves away. Extension I65 also serves to hold the bimetal assembly inthe position shown in Figure 12 until such time as lever I6I is movedmanually to the left, as seen in Figure 11. Upon such motion, projectionI61 engages extension I66 and lifts extension I65 out of engagement withprojecting portion I19. Since the breaking of contacts I58 and I59serves to break the circuit through coil I14, all as will be more fullyset forth hereinafter, the bimetal assembly will cool substantiallyimmediately after the cessation of heat in coil I14 and upon the raisingof extension I 65 by movement of manual reset lever I6I returns to' itsnormal or closed position. Contacts I 58 and I59 close and the devicewill be ready to repeat the previously described cycle of operation.

It may here be pointed out that due to the configuration of lever I6I,contacts I58 and I59 will not close until lever I6I has been manuallymoved to the left and released whereupon pressure of spring arm I54 andextension I63 against circular member I 68 and curved member I62,respectively, will return the switch to its normal right hand closedcircuit position. It will be noted that there is a clearance betweenprojection I61 and extension I66 and that due to this clearance uponmovement of lever I6I to the left, curved portion I62 will first engageextension I63 to move it to the right. After the clearance abovementioned has been closed, projection I61 will engage extension I66,which will inturn move circular member I68 a short distance to the rightuntil such time as extension I65 clears projection I19. Then uponrelease of lever I6I, the springpressure, as above described, willpermit the parts to return to normal position and the contacts I58 andI59 to close.

From the foregoing it will be seen that all stress on the movable partsof the device, such as projection I65 and contact bearing arms I54 andI55 is transmitted directly thereto from lever I6I and that no strainother than normal spring pressure is placed upon contact bearing arms I54 and I55. In other words, movement of lever I6I causes projection I61to move extensions I66 and I65 and circular member I68 to move contactarm I54, and pressure of arcuate portion I62 against extension I63causes movement of contact arm I55.

By this means the resiliency of arms I54 and I55 is less apt to beimpaired, the life of the switch is lengthened, and more efiicientoperation assured.

Referring nowto Figure 15 wherein is shown schematically one type ofsystem with which the structure of the instant invention may beadvantageously used, there are shown line wires I98 and I9I from whichpower enters the system from a suitable source (not shown). Wires I92and I93 connect the primary I94 01' transformer 6 I, which is of thestep-down type, having a secondary I95 across line wires I98 and I9I. Awire I96 leads from wire I9I to a suitable burner motor I91. A secondwire I98 terminates in one of contacts I45 from the other of which awire I99 extends to a. junction 288 from which a wire 28I leads to motorI91. A wire 282 leads from junction 288 to mercury switch I86 from whicha wire 283 leads to a suitable ignition device 284 which may take theform of a conventional step-up transformer. A wire 285 leads fromignition device 284 to line wire I9I.

It will thus be seen that when contacts I45 engage and are bridged byopposed contacts I35, in a manner to be described hereinafter, motor I91is energized, the circuit comprising line wire I9I, wire I96, motor I91,wire 28I, junction 288, wire I99, contacts I35 and I45, wire I98 to linewire I98.

It will also be 'seen that when the above mentioned contacts are closedand mercury switch I86 is closed, ignition device 284 is also energized,the circuit comprising line wire I98, wire I98, contacts I35 and I45,wire I99, junction 288, wire 282, mercury switch I86, wire 283, ignitiondevice 284, wire 285 to lme wire I9I.

A wire 2I8 leads from one side of transformer secondary I95 to a contact2 I I, which is positioned opposite a contact 2I2 carried by one arm ofa conventional bimetallic room thermostat 2I3. Thermostat 2I3 alsocarries a contact 2I4 adapt: ed to engage an opposed contact 2 I5 fromwhich a wire 2I6 leads to a junction 2I1. A wire 2I8 leads from junction2 I1 to contact 96. A wire 2 I 9 also leads from junction 2" to contactI28. From opposed contact 91, a. wire 228 leads to one terminal I 16 ofresistance element I14 and thence through the other of terminals I16 toa junction 22I. From junction 22I, a wire 222 leads to contact 88 and asecond wire 223 to relay coil II3. From the opposite side of relay II3,a wire 224 leads to one of terminals I56 adjacent arm I55 carryingcontact I59. The other of terminals I56 adjacent arm I54 carryingcontact I58 has a wire 225 leading therefrom to the opposite side oftransformer secondary I95. From a terminal 226 in electrical associationwith contacts 94, 95 and '81, a wire 221 leads to one of contacts II9.From the other of contacts II9, a wire 228 leads to a resistance 229from which a-wire 238 leads to a terminal 23I carried by thermostat 2I3.

In Figure 15, room thermostat 2I3 is shown in its hot, or inoperative,position. Assume now that there is a call for heat in the spacesurrounding thermostat 2I3, upon a given predetermined drop intemperature, contact 2I2 engages contact 2 and shortly thereafter, aftera subsequent predetermined drop, contacts M4 and 2I5 engage. Anenergizing circuit is now established from transformer I95 through wire2I8, contacts 2 and 2I2, 2I4 and 2I5, wire 2I6,'junc-, tion 2", wire2I8, contacts 96 and 94 through member 92, contacts 95 and 91, wire 228,resistance I14, junction 22I, wire 223, relay coil II3, wire 224, armI55, contacts I59 and I58, arm I54 and wire 225 back to transformersecondary I95. Relay coil II3 being energized, contacts I35 engage theiropposed contacts I45 to energize the motor circuit above described.Likewise, mercury switch I86 being closed, ignition device 284 will beenergized through the above described circuit. Simultaneously, uponclosing of contacts I45 and I35, contact I38 will engage contact I28 andcontacts I28 will engage their opposed contacts M9. This engagement wi lclose additional circuits, to be described hereinafter, which will beinoperative because of the fact that the circuit above described,through thermostat carried contacts 2G2 and. 2M and contacts and 9 3,offers the least resistance to the flow of current.

Assuming the parts to be in normal operating order, ignition device 2%ignites a fire fed by a burner motor [197] which occasions a relativelyrapid rise in temperature in the stack or flue in which is positionedthermostatic element 9 3. This rise in temperature causes an expansionof element and a consequent movement of rod 65 to the left in thedirection indicated by the arrow H. Such movement first opens contacts99 and Upon such opening, a circuit previously clcsed by theenergization of relay coil i is comprised of transformer secondary E95,wire 259, contacts 2M and 2E2, 2I5 and 2E5, wire 2H5, junction 2E1, wire2fl9,,contacts I29 and I99, i253 and H9, wire 22?], terminal 226, member92, contacts 95 and 97], wire 22!], resistance il l, junction 22E, wire223, relay coil Iii'i, wire 2224, contacts I59 and E55 and wire 225 backto transformer secondary I95 will continue to maintain relay coil i Itenergized and permit burner motor I91 and ignition device. 21% tooperate.

It should here be noted that both the energizing circuits abovedescribed pass through resistance Wt, of safety switch 53. If after apredetermined time, as illustratively 30 seconds, ignition device 2%fails to produce combustion in the burnerto occasion a consequenttemperature rise in the stack, or other space containing thermostaticelement 35, bimetal element I18 is heated, due to its juxtaposedposition to resistance I'M, and breaks contacts i58 and I59, which, aswill be seen from the consideration of the circuits traced above,immediately breaks the circuit, and permits relay coil H3 to bedeenergized and, consequently, opens contacts H35 and M5 to render thesystem inoperative until manually reset by means of manual reset leverISI (see Figure 11).

It should here be pointed out that should contacts 2M and M5 break atthis point, a third circuit will also pass through resistance I14. Thiscircuit is comprised of transformer secondary I95, wire 2H1, contacts 2and 2I2, thermostat 2I3, terminal 23I, wire 230, resistance 229, wire228, contacts H9 and I29, wire 221, junction 225, contacts 95 and 91,wire 220, resistance I14, junction 22f, wire 223, relay coil H3, wire224, member I55, contacts I59 and I58, member I56, and wire 225 back totransformer I95. While the above described circuit will be establishedonly on infrequent occasions since in normal operation contacts 2 and2I5 will not break until a temperature rise has been occasioned byenergization of burner I91, its occurrence is possible and in suchcontingency upon continued failure of ignition device 204 to createcombustion, contacts I58 and I59 are broken as above described.

Under normal circumstances, however, combustion is produced by ignitiondevice 204 and the temperature in the space containing element 35 rises.A continued rise causes rod 66 to move further towards the right tocause contact 81 to engage contact 88. A holding circuit is nowestablished comprised of transformer secondary I95,

arm contacts and 88, wire 222, junction 22H, wire relay coil M3, wire225, contacts 158 and wire 225, back to transformer secondary G95. Thiscircuit, of course, continues to energize relay coil 0 iii to maintainburner l91 and ignition device 25 5- in operation, but resistance ll'id,wire 22d, contacts and 90, arm 92, contacts 9 3 and 95 and wire 2 it arenow shunted out.

A continued increase in stack temperature adjacent element 95 causes theopening of ,contacts and M, which now has no efiect on the circuitssince these contacts are shunted out by the circuit describedimmediately above. After contact 95 breaks from contact 91, mercuryswitch M6 is tilted by the movement of extension i 99 of arm 92 to openposition to deenergize ignition device 204, and burner I91 continues tooperate as long as there is a call for heat indicated by the position ofthermostat 2I3.' The operation of burner motor I91 in the course of timeraises the temperature in the space containing thermostat 2I3 "to apredetermined point at which contacts 2 and 2I5 break.

A new holding circuit is now established which comprises transformersecondary I95, wire 2IU, contacts 2I I and 2I2, thermostat 2I3, terminal23I,- wire 239, resistance 229, wire 229, contacts M9 and I29, wire 221,terminal 226, arm 85, contacts 81 and 88, wire 222, junction 22I, wire223, relay coil H3, wire 224, contacts I58 and I59, wire 225 back totransformer secondary I95.

It should be noted here that the circuit above described was previouslymade upon the closing of relay 62 and contacts 81 and 88 but due toresistance 229, was shunted out by the closure of contacts 2 I4 and 2I5. However, the breaking of contacts 2M and 2I5 renders this abovedescribed circuit operative and passage of current through resistance229 heats the same which since it is positioned adjacent thermostat 2I3occasions an oscillation of the movement thereof by the addition offalse heat thereto and consequent rapid breaking of contacts 2 and 2I2,thereby decreasing the differential of operation of the thermostat.Immediately, upon the breakage of the latter two contacts, the system iscompletely deenergized, burner motor I91 ceases to operate and the partsafter an interval return to their cold position. Upon cooling of thetemperature in the space in which is mounted element 34, rod 66 moves tothe right and first breaks contacts 81 and 88, then moves mercury switchI06 to its closed position, then causes contact 94 to engage contact 96and finally contact 95 to engagecontact 91, whereupon the parts will bein their normal operating position and ready for a further call for heatby thermostat 2 I 3.

It should here be noted that in the event of flame failure at any timeduring the operation of the device, a drop in temperature adjacentelement 34 causes a relatively immediate movement of rod 66 to the rightto open contacts 81 and 88 and that such opening occurs prior to themaking of contacts 94 and 96 or 95 and 91 and, accordingly, results inthe deenergization of the system. The system then automatically recyclesand after a predetermined period sufficient to permit cooling of thestack temperature, assuming that thermostat 2I3 still calls for heat,the energizing circuit first described is reestablished and upon acontinued flame failure for a predetermined period of, as abovementioned, thirty seconds, the safety switch 63 operates to breakcontacts I58 and I59 and completely deenergize the system until manuallyreset as'described above.

From the foregoing it will be seen that there is herein provided animproved mechanism which will occasion accurate operation of a system asabove described in a satisfactory and efficient manner and which willprovide all of the usual safety features in connection with an oilburner system.

It will also be seen that there is provided in the structure abovedescribed an instrument capable of realizing the objects of theinvention including many advantages of great practical importance.

As many possible embodiments may be made in the above structure and asmany modifications maybe made in the above embodiment, it is to beunderstood that all matterhereinbefore set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

I claim as my invention:

1. A device of the character describedjcomprising, in combination, acondition responsive means, a linearly movable element associatedtherewith, hence movable in response to condition change, a pair ofoppositely disposed arcuate surfaced members tangentially disposed withrespect to said element and in frictional engagement therewith, armssubstantially rigidly associated with said members, and circuitcontrolling means disposed on said arms whereby linear movement of saidelement is transmitted to arcuate movement of said circuit controllingmeans.

2. A device of the character described, comprising, in combination, alinearly movable relatively rigid bar, a condition responsive elementassociated with an end thereof and adapted to move said bar uponcondition change, a pair of oppositely disposed arcuate surfaced membersrevolvably mounted adjacent the end of said bar opposite said elementand on opposite sides thereof in frictional engagement therewith,resilient means holding said members in said frictional engagement, andcircuit controlling means operated by said members.

3. A device of the character described, comprising, in combination, alinearly movable relatively rigid rod, a condition responsive elementassociated with an end of said rod and adapted to move the same uponcondition change, a pair of oppositely disposed substantially parallelrollers revolvably mounted adjacent the opposite end of said rod andfrictionally engaging therewith upon opposite sides thereof, mountingmeans for said rollers comprising a pin extending through each of saidrollers and extending a relatively substantial distance beyond the axialextremities thereof, supports for said pins, spring means disposedbetween adjacent ends of said pins whereby said rollers are drawninwardly toward the periphery of said rod, arms carried by each of saidrollers whereby upon rotation of said rollers by movement of said rodsaid arms are moved through an arcuate path, contact members disposed onsaid arms and additional contact members positioned in the path ofmovement of said first mentioned contact members and adapted to beengaged thereby.

4. A device of the character described, comprising, in combination, acondition responsive means, a substantially straight element movedlongitudinally thereby, a circuit controlling means, means connectingsaid circuit controlling means to said element, said last mentionedmeans comprising a member having an arcuate extremity'frictionally'engaging a peripheral surface of said element and tangentially disposedwith respect thereto, means for maintaining said element in engagementwith said member comprising a spring and roller engaging said element,means to limit the movement of said circuit controlling means wherebyupon movement of said element within said limit a rolling motion will beimparted through said arcuate extremity to said member but upon motionbeyond said limit said element will slip with respect to said member.

5. A slip friction mechanism, comprising, in combination, a linearlymovable element, a pair of parallel rollers oppositely disposed andtangential to the periphery of said element, spring means tending todraw said rollers towards each other v and hence into frictionalengagement with said 6. A switching mechanism comprising, incombination, a condition responsive element, a linearly movable rodadapted to be actuated thereby, a switch, and means associated with saidrod to control the opening and closing of said switch, said lastmentioned means comprising a roller, a. contact carrying member rigidlyassociated with said roller, said roller being positioned tangential toand in frictional engagement with a peripheral portion of said rodwhereby condition change serves to actuate said element to impart motionto said rod and hence to said switch controlling member to open or closesaid switch.

'I. A switching mechanism comprising, in combination, a conditionresponsive element, a linearly movable rod actuated'thereby, a pluralityof contacts and means associated with said element to actuate saidplurality of contacts, said last mentioned means comprising rollers infrictional engagement with a peripheral portion of said rod and armsbearing said contacts mounted on said rollers.

8. A device of the character described comprising in combination, a rodmovable longitudinally in response to variations in temperature, arevolvable member having a rounded channel shaped portion in frictionalengagement with said rod, and circuit controlling means actuated by saidmember.

9. A device of the character described comprising in combination, a rodmovable longitudinally in response to variations in temperature, arevolvable member having a rounded channel shaped portion in frictionalengagement with said rod, a movable contact carried by said mem her, astationary contact for cooperation therewith, and a mercury switchcarried by said element and adapted to be actuated upon longitudinalmovement of said rod.

10. A slip friction mechanism comprising in combination, alongitudinally movable rod, an axle, a roller mounted on said axle, asupport, slots in said support, said axle being mounted in said slots,resilient means holding said roller in engagement with said rod, andstops limiting the rotative movement of said roller whereby uponmovement of said rod in one direction said roller will rotate againstone of its stops and on further movement of said rod in thesamedirection said roller will slip with respect to said rod.

11. In a device of the character described comprising in combination, asubstantially straight actuating member, a rotatably mountedactueasement with said actuating her, no to cause longitudinal movementof said and t= ing member response to changes in n con i== tion, stopsfor limiting the rotation of ac toot-ed member, and. resilient means onsaid actuated member to hold it in engagement with said actuatinginemhei,

12. In a device of the charactei" desctlfoed com= MD prising incombination, a longitudinally -5 able hat, means for the one hack forthin response to condition variations, a psi? of friction membersengaging" opposite sides said loar, spring means connected hetween s dmembers and holding them in engagement W said has, and means for themovement of said members.

13. In a device of the character described com prising in combination, alongitudinally movable hat, heat responsive moving has loacl: forth, apelt of ction elements en= gaging opposite sides of satin hat, optimeniaextending between said elements and hold ,1,

them in engagem nt oot, niovalole con=- tacts mounted on on elements,

stationary contacts for cooperation sol d movable contacts, saidstationary contacts H1343" iting the movement of said friction elements.

in a device of the character described con: so prising in combination, alongitudinally mow able bar, a pair of friction elements opposite sidesof the loan, spring means extend ins between said elements to hold themin en= gagement with said Tear, movable contacts on said elements,stationary contacts, responsive means for moving said hat in onedirectime to first disengage the movable contact one element fromstationary contest and then engage the movable contact on the othereleno ment with its stationary contact, and stop for limiting themovement of said one element from its stationary contact, said oneelement slip= pine with relation to said has on its continued movementin said one direction.

it. A slip friction switchingmechanism coinprising in combination, alongitudinally movable bar, a pair of friction elements engaging opposite sides of said bar, a pair of contacts moved by one of saidelements, a pair of stationery con- 5 tacts cooperating therewith, acontact moved by the other of said elements, a stationary contact forcooperation therewith, and a thermostat for moving said has in onedirection to first cause said one element to move one oi its contacts55; out of engagement with its stationery contect, then said otherelement to move its contact into engagement with its stationery contactwhich said other element slips with respect to s her, then said oneelement 1 to contact out of engagement contact, otter which saris one astop and sl ce further mov direction.

mo 7o @IQEELSELE'EL W o' tection, s

contact out of contact, then cause SELL;

said other c t tact into tic elel can, a

lng said in one one element en age'n s other element to inent e itsstatlonai'y c alto" rni other element slips with to one element to moveits e1 con engagement with s1 which one element 51:. c top and slip withrespect to has on other moveme t 0). said has in said one direction,said thermostat moving said TQM in direction to first cause said otherlement to move its contact out of engagement with its stationary and tothen cause said one element to move its said other contact then one intoengagement with their respective ste onai'y contacts after which saidone element slips with respect to "not, a stop positioned for engag soment on said other element to cause it to slip i'espect to and a mercuryswitch actuated loy one element.

it. In o device of the character descri ed com-- prising in combination,9, longitudinally movalle to hat, a pair of lndependei Ely mounted frction elements opposit sides of t least one open contact sx element, ndnicictm actnat novice the ionisin l combine ion, a l l menihei, a

emcee Peace 1 ments, and means for limiting the movement of saidelements.

21. In a device of the character described comprising in combination, alongitudinally movable member, means for moving said member back andforth in response to condition variations, 9.

pair of friction elements engaging opposite sides of said member, asingle spring means operative to hold said member and said elements infrictional engagement, and means for limiting the movement of saidelements.

ERNEST M. MILLER.

